Scherer and Petry • SEASONAL VARIATION IN SHOREBIRD ABUNDANCE 
43 
14000 ■ 
12000 ■ 
10000 ■ 
o 8000 
ONDJ FMAMJJASONDJ FMAMJ J AS 
2007- 2009 
FIG. 2. Monthly abundance of shorebirds (Charadriidae and Scolopacidae) from October 2007 to September 2009 on 
the coast of Rio Grande do Sul. southern Brazil. 
regular with greatest abundance occurring between 
October and February (n = 353 in Feb 2009) tuid 
lowest between April and September, this species 
was absent in June and July. 
The frequency of occurrence of Semipalmated 
Plovers (Charadrius semlpalmutus ) was sporadic 
'»the 2007/2008 period and regular in 2008/2009. 
ihe greatest abundance was recorded between 
February and March 2008, and between April and 
May 2009 with no records of occurrence between 
( Mober and January in either year. The frequency 
of occurrence of Collared Plovers was regular 
and the species was recorded in all months. The 
greatest abundance of this species occurred 
between March and August, and was lowest 
between September and February. A large part 
of the increase in abundance beginning in March 
was due to the presence of young of the year, 
which were observed foraging in the w'ash zone 
and near the drainage sandbars of lakes. Abun¬ 
dance was considerably higher in May, June, and 
August 2008 than during the same period in 2009. 
TABLE 2. Frequency of occurrence (C) of shorebirds from October 2007 to September 2009 
Orande do Sul, southern Brazil. 
Oct 2007 to Sep 2008 
Oct 2008 to Sep 2009 
Specie* 
c 
Constancy 
C 
Constancy 
c 
Southern Lapwing 
100 
Regular 
100 
Regular 
100 
American Golden Plover 
8 
Occasional 
33 
Sporadic 
21 
Grey Plover 
58 
Constant 
83 
Regular 
71 
Semipalmated Plover 
33 
Sporadic 
50 
Regular 
42 
Collared Plover 
100 
Regular 
UK) 
Regular 
100 
Rufous-chested Plover 
8 
Occasional 
8 
Occasional 
8 
Uudsonian Godwii 
0 
Absent 
8 
Occasional 
8 
'A'himbrel 
0 
Absent 
33 
Sporadic 
17 
Solitary Sandpiper 
33 
Sporadic 
17 
Occasional 
25 
Greater Yellowlegs 
50 
Regular 
67 
Regular 
58 
^ csser Yellowlegs 
83 
Regular 
92 
Regular 
88 
Ruddy Turnstone 
67 
Regular 
58 
Regular 
63 
Red Knot 
67 
Regular 
33 
Sporadic 
58 
Sanderling 
100 
Regular 
100 
Regular 
100 
Semipalmated Sandpiper 
8 
Occasional 
8 
Occasional 
8 
vv hiic-rumped Sandpiper 
83 
Regular 
67 
Regular 
75 
Ruff-breasted Sandpiper 
8 
Occasional 
8 
Occasional 
8 
2007 to 2000 
Constancy 
Occasional 
Occasional 
